AT 508776 discloses a method for pre-heating an annealing material in a hood-type annealing system with annealing pedestals that accommodate the annealing material under a protective hood in a transport fluid atmosphere. The annealing material to be subjected to a heat treatment in a protective hood is pre-heated with the aid of a gaseous heat transfer medium that flows around the protective hoods from the outside in a circuit, wherein said heat transfer medium absorbs heat from annealing material that has already been heat-treated in one protective hood and emits heat to annealing material to be pre-heated in another hood. At least one further annealing pedestal with a protective hood that can be heated from the outside by means of burners is used for the heat treatment of the annealing material. The hot exhaust gases from the heating unit of this protective hood are admixed to the heated heat transfer medium for pre-heating the annealing material.
AT 507423 discloses a method for pre-heating an annealing material in a hood-type annealing system with two annealing pedestals that accommodate the annealing material under a protective hood. The annealing material to be subjected to a heat treatment in a protective hood is pre-heated with the aid of a gaseous heat transfer medium that is circulated between the two protective hoods, wherein said heat transfer medium absorbs heat from the annealing material heat-treated in one protective hood and emits heat to the annealing material to be pre-heated in another protective hood. The circulated heat transfer medium flows around the two protective hoods from the outside while a transport fluid is circulated within the protective hoods.
AT 411904 discloses a hood-type annealing furnace, in particular for steel strip or wire coils, with an annealing pedestal that accommodates the annealing material and with a protective hood placed thereon in a gas-tight fashion. Furthermore, a radial fan is mounted in the annealing pedestal, which radial fan comprises an impeller as well as a guide apparatus that encloses the impeller and serves for circulating a transport fluid in the protective hood. A heat exchanger for cooling the transport fluid is at the input side connected to the pressure side of the radial fan via a flow channel and at the output side leads into an annular gap between the guide apparatus and the protective hood. A deflection device that can be axially displaced into the flow path of the radial fan at the pressure side serves for selectively connecting the flow channel leading to the heat exchanger (water-cooled annular tube bank) to the radial fan. The protective hood is mounted in a gas-tight fashion by means of an annular flange, namely pressed onto the pedestal flange. The heat exchanger (cooler) is located underneath the annular flange. The flow channel consists of an annular channel that originates at the outer circumference of the guide apparatus and is arranged concentric to the annular gap. The deflection device is realized in the form of an annular sliding baffle that encloses the guide apparatus on the outside.
Conventional batch-operated furnaces have a relatively high energy consumption.